The delivery of medicament through a person's skin utilizing electrophoresis is well known where the drug is one whose molecules are ionic in solution or suspension. The solution or suspension is made subject to an electric field and if the electrode having the same charge as that of the ions is above the solution adjacent the skin which is the site of administration, the ions will be repelled and migrate through the skin into the blood stream.
A variety of problems associated with this technique have limited severly the extent of the use of this type of apparatus. Reference to or disclosure of such apparati is shown in the following U.S. Patents, where it will be noted that there is great emphasis in developing electrodes which are disposable and/or more effective:
U.S. Pat. Nos. 2,492,155; 3,163,166; 3,289,671; 3,677,268; 4,141,359; 4,166,457; 4,239,052; 4,243,052; 4,250,878; 4,273,135; 4,367,745.
It will be noted from U.S. Pat. Nos. 3,289,671 and 4,141,359, in particular, that the rate of drug delivery is a function of current flow and that control over current flow is crucial to having the correct amount of medicament applied.
There have also been attempts to provide an apparatus for such electrotherapy which is self-contained, so that the patient can wear the device carrying on normal activities while the drug is being administered. Devices of this type are disclosed in U.S. Pat. Nos. 385,556, 486,902, and 2,784,715.
One problem with such prior art devices was that they were bulky and lacked the necessary drug delivery rate control.
Another significant problem associated with such prior art devices is that the user, in wearing the device, was unable to determine whether the drug was being administered, and more particularly whether the drug was being administered in the proper desired dosage.
Now there is provided by the present invention, an indicator which is formed with a compact electrophoretic drug delivery device so as to positively indicate the flow of the proper dosage of medicament.